Threaded screw fasteners for high-production assembly are in some instances provided with integral pilot drilling tip or entering portions so designed that the screw will drill its own pilot hole in the work and then form and/or cut threads in the work as it is driven home to the final holding position by a suitable rotary driving tool. Such screws may be formed by pinching and rolling dies, for example in the manner disclosed in U.S. Pat. to Skierski, No. 3,550,255, granted Dec. 29, 1970. Said patent, and related Skierski U.S. Pat. No. 3,395,603, granted Aug. 6, 1968 also disclose a drill screw formed in the indicated manner.
The overall objective of the present invention is to provide an improved drill screw adapted to be formed by pinching and rolling processes, which provides high strength, and which is installable with relatively low driving torque.
Other objects and advantages will become apparent upon consideration of the present disclosure in its entirety.